Localizer antenna system



Nov. 18, 1958 A. ALFORD LocALzER ANTENNA SYSTEM original Filed Feb. 5, 1951 nited States Patent 2,861,266 LOCALIZER ANTENNA SYSTEM Andrew Alford, Winchester, Mass.

Original application February 5, 1951, Serial No. 209,431. and this application July 16, 1953, Serial No.

`6 Claims. (Cl. 343-792) The present invention is a division of my copending application Serial No. 209,431, tiled February 5, 1951, now Patent No. 2,682,050, and is a copy of the application mentioned above as tiled.

The present invention relates to a combination antenna array and more particularly to an antenna structure adapted for such uses as a localizer antenna system disclosed in the above mentioned application. The particular type of array and system for which the present invention was particularly designed is described and illustrated in the above mentioned application. However it is understood that this particular device may be used in systems where the particular radiation pattern derived and the structure arrangement are desirable.

The present invention may be utilized in pairs to obtain a radiation pattern having a pair of closely adjacent major lobes. Such device may be used in an array in conjunction with other antennae to produce a unidirectional radiation pattern having in substance two adjacent highly developed lobes extending substantially in the same direction. This array may in turn form a component in a localizer system.

Without further describing the merits and advantages of the present invention, the invention will be described in connection with the drawings illustrating an embodiment thereof, in which:

Figure l shows in cross sectional elevation the full Wave dipole of the present invention.

Figure 2 represents a calculated pattern of the radiation of the elements shown in Fig. l.

The radiators are a full wave length and a full section of the structures for these radiators is shown in Figure 1. This structure is essentially an array of two half wave length elements placed next to each other. The feeding arrangement, however, is simpler.than that for a half Wave element.

The outer conductors of the two half wave elements consist of two Ts 51 and 52 which in section may be cylindrical, oval or other type of section commonly used as a coaxially transmission line. I-Iere the conductor designated as cylindrical is intended to include other types of sections as well. The full wave element is fed through the stem of one T. This comprises the outer conductive cylinder 53 and the inner cylinder 54 forming a coaxial transmission line. The inner cylinder 54 is spaced and insulated from the outer cylinder and is connected at its top to the inner conductor 56 concentrically positioned within the right half of the outer cross bar 55 by the conductive strap 57. The inner conductor 56 is insulated by suitable insulator disks from the outer conductor 55 and connects through insulating end cap 58 to the cap 62 of the cross bar of the outer conductor 63 of the T at the right in Figure l. A conductive strap 59 makes a good conductive connection from the terminal 60 to the terminal 61 of the conductive cap 62, at the inner end of the cylinder 63 which forms the cross bar for the T 52.

In a construction which I have successfully used,

Patented `Nor. 18, ,19,58

ice

2 the impedance between the ends ,ofthe Ts was approximately 650 ohms matched to a 52.5' ohmllle by a'transformer having a Z0 of 184 ohms.

The -design of the full-wavelelementis suchkthat there are small currents ilowing along the,.s ter ns of both Ts. These currents flow in opposite directions in the two stems. At rst it was believed that this might result in excessive radiation or perhaps even in minor loads in the direction at right angles to the stems. The only effect `of the stem currents is to broaden slightly the radiation pattern.

A calculated pattern of the radiation of a pair of the type of antenna illustrated when energized in phase opposition results in a pattern shown in Figure 2. This calculated pattern shows that there are two sets of auxiliary lobes on the outer side of the pair of main lobes and that in this case the main and auxiliary lobes tend to be relatively narrow.

I claim:

1. In a localizer system a full wave unidirectional radiator comprising two one half wave T-type radiators, each having coplanar stems and cross bars with the cross bars being longitudinally aligned, means for feeding one of said radiators through the stem of its T and from the stem into one side of the cross bar of said T out through the end thereof to the adjacent end 'of the cross bar of said other T.

2. In a localizer system a full Wave unidirectional radiator comprising two half wave T-type radiators substantially coplanarly aligned one with the other with one end of the cross bar of one of the Ts adjacent an end of the cross bar of the other of the Ts, means providing an insulating cap on one of said adjacent ends of one of said cross bars, a conductive connection extending through said insulating cap to the adjacent end of the cross bar of said other T and means feeding said rst T through its stem with an inner conductor connecting to said conductive connection.

3. A full wave unidirectional radiator comprising two T-shaped similar radiators, each formed of cylindrical tubes, one of said T-shaped radiators having a stem section and one branch section formed as a coaxial cable with the internal conductors and the external conductors connected together respectively and the other T formed solely of cylindrical tubes, and a conductive connection from the internal conductor of one branch of one T to a branch of the other T.

4. A full wave radiator comprising two T-shaped similar radiators, each formed of cylindrical tubes, one of said T-shaped radiators having a stem section and one branch section formed as a coaxial cable with the internal conductors connected together respectively and the other T formed solely of cylindrical tubes, said internal conductor of said one branch projecting beyond the end of the external conductor, a cap having a shoulder threading over the end of said external conductor, an insulating disc through which the internal conductor projects fitting on the end of said external conductor securing the internal conductor and sealing the same at the end of the external conductor under said cap which clamps the same to said external conductor and a conductive connection from the internal conductor of one branch of one T to a branch of the other T.

5. In a localizer system, a full Wave radiator comprising two one-half wave T-type radiators having coplanar cross arms and stems with said cross arms longitudinally aligned, one T having coaxial conductors forming continuous elements in the stern and one side cross arm of said T, the other comprising a single con ductive T of a size of the external conductor of the first T and conductive connection from the internal conductor at the end of the side cross arm to said single conductive T.

6. A full wave radiator comprising two T-shaped similar radiators, one of said radiators comprising a stem and branch, each of said last mentioned elements having continuous external and internal conductors, means insulating said internal conductors from said externalconductors, conductive connecting means projecting from said internal conductor at the end of said branch and References Cited in the tile of this patent i radiator, said latter radiator being a single conductor.

UNITED STATES PATENTS Brown May 9, 1939 Brown Mar. 11, 1947 Kandoian Mar. 29, 1949 FOREIGN PATENTS Germany Jan. 15, 1953 

